Electrode body for use in non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery

ABSTRACT

In an electrode body for use in non-aqueous electrolyte secondary battery, a first end of a separator is located more interiorly than one positive electrode end of a positive electrode plate in a width direction, located more exteriorly than one end of a coated positive electrode portion of the positive electrode plate, and located more exteriorly than one end of a coated negative electrode portion of a negative electrode plate. The first end of the separator is thicker than an intermediate portion. A second end of the separator is located more interiorly than an other negative electrode end of the negative electrode plate in the width direction, located more exteriorly than the other end of the coated positive electrode portion of the positive electrode plate, and located more exteriorly than an other end of the coated negative electrode portion of the negative electrode plate. The second end of the separator is thicker than the intermediate portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application based upon and claims thebenefit of the prior PCT International Patent Application No.PCT/JP2010/051718 filed on Feb. 5, 2010, the entire contents of whichare incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an electrode body for use innon-aqueous electrolyte secondary battery and a non-aqueous electrolytesecondary battery using the electrode body.

BACKGROUND ART

Non-aqueous electrolyte secondary batteries such as lithium ionsecondary batteries have gained considerable interest as electric powersources for portable devices and as electric power sources for drivingvehicles such as electric cars and hybrid electric vehicles. One knownnon-aqueous electrolyte secondary battery has an electrode body whichhas a positive electrode plate, a negative electrode plate and aseparator interposed between the positive and negative electrode plates,the positive and negative electrode plates and the separator overlappingone another with their widths oriented in the same direction (see e.g.,Patent Literatures 1 to 3).

CITATION LIST Patent Literatures

-   Patent Literature 1: JP6 (1994)-150900A-   Patent Literature 2: JP2004-95382A-   Patent Literature 3: JP2006-278245A

The non-aqueous electrolyte secondary batteries such as described aboveare sometimes heated to high temperature owing to heat generation of thebattery caused by overcharge or the like so that heat shrinkage of theseparator occurs in its width direction. If the separator thermallyshrinks in the width direction, the separator becomes absent between thepositive and negative electrode plates at the widthwise ends, so thatthe positive and negative electrode plates are likely to come intocontact with each other, causing electrical short circuit. This internalshort circuit could lead to further battery heat generation.

With the intent of overcoming the above problem, Patent Literature 1 hasproposed the following non-aqueous electrolyte secondary battery.According to Patent Literature 1, positive and negative electrode platesand a separator which is wider than these electrode plates are used, anda rolled-up electrode body is formed by winding the positive andnegative electrode plates and the separator such that the widthwise endsof the separator (i.e., first and second ends located at one end and theother end, respectively, of the separator with respect to its widthdirection) project outwardly from one end (upper end) and the other end(lower end) of the electrode body. Then, the excessive end portions ofthe separator (the first and second ends of the separator) outwardlyprotruding from the one end (upper end) and the other end (lower end) ofthe rolled-up electrode body are heated and thereby thermally shrunken.The excessive end portions of the separator are thus thermallycontracted beforehand, thereby inhibiting the heat shrinkage of theexcessive end portions of the separator during heat generation of thebattery to prevent the contact between the positive and negativeelectrode plates at the widthwise ends (upper and lower ends).

Another non-aqueous electrolyte secondary battery is disclosed in PatentLiterature 2. This battery is composed of a positive electrode platehaving positive electrode mixture layers applied to the surfaces of apositive current collector (aluminum foil); a negative electrode platehaving negative electrode mixture layers applied to the surfaces of anegative current collector (copper foil); and a separator wider thanthese electrode plates. The positive and negative electrode plates andthe separator are wound to form a rolled-up electrode body such that thewidthwise ends of the separator (i.e., first and second ends located atone end and the other end, respectively, of the separator with respectto its width direction) project outwardly from one end and the other endof the electrode body. Fixedly attached to both widthwise ends of thepositive electrode plate are insulating films to which fine particles(such as aluminum) having a heat resistance of 500° C. or more arebonded by binder resin. The widthwise ends of the negative electrodeplate are also provided with insulating films fixed thereto, theseinsulating films containing fine particles (such as aluminum) which arebonded to the insulating films by binder resin and have a heatresistance of 500° C. or more. This prevents occurrence of internalshort circuit between the positive and negative electrodes, because theinsulating films attached to the positive and negative electrode platescome into contact with each other in the event that the separatorbecomes absent between the positive and negative electrode plates at thewidthwise ends owing to shrinkage of the separator in a width directioncaused by heat generation of the battery.

SUMMARY OF INVENTION

Technical Problem

The non-aqueous electrolyte secondary battery disclosed in PatentLiterature 3 has a rolled-up electrode body in which a first separatorend (i.e., the end located at one end of the separator with respect toits width direction) is located more interiorly with respect to thewidth direction than one positive electrode end (i.e., the end locatedat one end of the positive electrode plate with respect to its widthdirection), whereas a second separator end (i.e., the end located at theother end of the separator with respect to its width direction) islocated more interiorly with respect to the width direction than another negative electrode end (i.e., the end located at the other end ofthe negative electrode plate with respect to its width direction). Inother words, the rolled-up electrode body is formed by winding such thatthe one positive electrode end is more exteriorly located than the firstseparator end with respect to the width direction whereas the othernegative electrode end is more exteriorly located than the secondseparator end with respect to the width direction. The one positiveelectrode end is constituted by an uncoated positive electrode portion(or a part thereof) of the positive electrode plate which portion is notcoated with the positive electrode mixture layers, and the positiveelectrode plate and the positive terminal are electrically connected toeach other by welding the one positive electrode end to the positiveterminal. The other negative electrode end is constituted by an uncoatednegative electrode portion (or a part thereof) of the negative electrodeplate which portion is not coated with the negative electrode mixturelayers, and the negative electrode plate and the negative terminal areelectrically connected to each other by welding the other negativeelectrode end to the negative terminal.

Such a non-aqueous electrolyte secondary battery is still somewhatexposed to the risk of electrical short circuit that is caused asdescribed earlier by the contact between the positive electrode plateand the negative electrode plate at the widthwise ends when theseparator thermally shrinks in the width direction due to battery heatgeneration or the like. In this battery, since the separator does notprotrude outwardly from one end and the other end of the rolled-upelectrode body (that is, the separator has no excessive end portions),the heating and heat shrinkage of the excessive end portions of theseparator such as seen in Patent Literature 1 cannot be carried out. Thetechnique disclosed in Patent Literature 2 has not proved to be usefulbecause insulating resin needs to be prepared and applied to thewidthwise ends of the positive and negative electrode plates, whichinvolves troublesome manufacturing processes and, in consequence, incurshigh costs.

The invention is directed to overcoming the foregoing problems and aprimary object of the invention is therefore to provide an electrodebody for use in non-aqueous electrolyte secondary battery and anon-aqueous electrolyte secondary battery which are capable ofpreventing “the undesirable electric short circuit caused by the contactbetween the positive electrode plate and the negative electrode plate atthe widthwise ends due to heat shrinkage of the separator in the widthdirection”.

Solution to Problem

According to one aspect of the invention, there is provided an electrodebody for use in non-aqueous electrolyte secondary battery, the electrodebody comprising a positive electrode plate, a negative electrode plateand a separator interposed between the positive and negative electrodeplates, the positive electrode plate, negative electrode plate andseparator overlapping one another with their widths oriented in the samedirection, wherein the positive electrode plate has a positive currentcollector and a positive electrode mixture layer applied to a surface ofthe positive current collector; the negative electrode plate has anegative current collector and a negative electrode mixture layerapplied to a surface of the negative current collector; the separatorhas a first end located at one end thereof and a second end located atthe other end thereof with respect to a width direction and has anintermediate portion located between the first and second ends; withrespect to the width direction, the first separator end is located moreinteriorly than one positive electrode end which is located at one endof the positive electrode plate with respect to the width direction;located more exteriorly than one end of a coated positive electrodeportion of the positive electrode plate which portion is coated with thepositive electrode mixture layer; and located more exteriorly than oneend of a coated negative electrode portion of the negative electrodeplate which portion is coated with the negative electrode mixture layer,the first separator end being thicker than the intermediate portion; andwith respect to the width direction, the second separator end is locatedmore interiorly than an other negative electrode end which is located atan other end of the negative electrode plate with respect to the widthdirection; located more exteriorly than an other end of the coatedpositive electrode portion; and located more exteriorly than an otherend of the coated negative electrode portion, the second separator endbeing thicker than the intermediate portion.

In the above-described electrode body for use in non-aqueous electrolytesecondary battery, the separator has a first end located at one endthereof, a second end located at the other end thereof, and anintermediate portion located between the first and second ends, withrespect to its width direction.

Of these portions, the first separator end is located more interiorlythan one positive electrode end with respect to the width directionwhich end is located at one end of the positive electrode plate withrespect to the width direction. In other words, this one positiveelectrode end is located more exteriorly than the first separator endwith respect to the width direction. This one positive electrode end iscomposed of, for instance, an uncoated positive electrode portion (or apart thereof) of the positive electrode plate which portion is notcoated with the positive electrode mixture layer. In this case, thepositive electrode plate and the positive terminal can be electricallyconnected to each other by welding the one positive electrode end to thepositive terminal.

The second separator end is located more interiorly than an othernegative electrode end with respect to the width direction which end islocated at an other end of the negative electrode plate with respect tothe width direction. In other words, the other negative electrode end islocated more exteriorly than the second separator end with respect tothe width direction. This other negative electrode end is composed of,for instance, an uncoated negative electrode portion (or a part thereof)of the negative electrode plate which portion is not coated with thenegative electrode mixture layer. In this case, the negative electrodeplate and the negative terminal are electrically connected to each otherby welding the other negative electrode end to the negative terminal.

Further, with respect to the width direction, the first separator end islocated more exteriorly than one end of a coated positive electrodeportion of the positive electrode plate which portion is coated with thepositive electrode mixture layer and located more exteriorly than oneend (that corresponds to one end of the negative electrode plate) of acoated negative electrode portion of the negative electrode plate whichportion is coated with the negative electrode mixture layer. Inaddition, the first separator end is thicker than the intermediateportion.

Further, with respect to the width direction, the second separator endis located more exteriorly than an other end (that corresponds to another end of the positive electrode plate) of the coated positiveelectrode portion and located more exteriorly than an other end of thecoated negative electrode portion. In addition, the second separator endis thicker than the intermediate portion.

Therefore, use of the above-described electrode body in a non-aqueouselectrolyte secondary battery makes it possible to prevent “theundesirable electric short circuit caused by the contact between thepositive electrode plate and the negative electrode plate at thewidthwise ends due to heat shrinkage of the separator in the widthdirection”.

For example, even if the separator thermally shrinks in the widthdirection so that the first separator end is displaced inwardly (towardthe other end) in the width direction whereas the second separator endbeing displaced inwardly (toward the one end) in the width direction,the first separator end will strike against the end face of at leasteither the one end of the coated positive electrode portion or the oneend of the coated negative electrode portion and therefore will beunable to further move inwardly in the width direction (toward the otherend), thanks to the configuration of the first and second separator endswhich are thicker than the intermediate portion. Further, the secondseparator end will strike against the end face of either the other endof the coated positive electrode portion or the other end of the coatednegative electrode portion and therefore will be unable to further moveinwardly in the width direction (toward the one end). This enables it tokeep the separator present between the positive and negative electrodeplates with respect to the width direction, thereby maintaining theelectrical insulation between the positive and negative electrodeplates.

One form of the configuration in which the first and second separatorends are thicker than the intermediate portion is such that the firstand second separator ends are folded back on themselves (e.g., foldeddouble) thereby to make them thicker (e.g., twice thicker) than theintermediate portion.

According to another aspect of the invention, there is provided anelectrode body for use in non-aqueous electrolyte secondary battery, theelectrode body comprising a positive electrode plate, a negativeelectrode plate and a separator interposed between the positive andnegative electrode plates, the positive electrode plate, negativeelectrode plate and separator overlapping one another with their widthsoriented in the same direction, wherein the positive electrode plate hasa positive current collector and a positive electrode mixture layerapplied to a surface of the positive current collector; the negativeelectrode plate has a negative current collector and a negativeelectrode mixture layer applied to a surface of the negative currentcollector; the separator has a first end located at one end thereof anda second end located at the other end thereof with respect to a widthdirection and has an intermediate portion located between the first andsecond ends; with respect to the width direction, the first separatorend is located more interiorly than one positive electrode end which islocated at one end of the positive electrode plate with respect to thewidth direction; located more exteriorly than one end of a coatedpositive electrode portion of the positive electrode plate which portionis coated with the positive electrode mixture layer; and located moreexteriorly than one end of a coated negative electrode portion of thenegative electrode plate which portion is coated with the negativeelectrode mixture layer, the first separator end being thermallyshrunken by heating beforehand; and with respect to the width direction,the second separator end is located more interiorly than an othernegative electrode end which is located at an other end of the negativeelectrode plate with respect to the width direction; located moreexteriorly than an other end of the coated positive electrode portion;and located more exteriorly than an other end of the coated negativeelectrode portion, the second separator end being thermally shrunken byheating beforehand.

In the above-described electrode body for use in non-aqueous electrolytesecondary battery, the first separator end is located more interiorlythan one positive electrode end with respect to the width directionwhich end is located at one end of the positive electrode plate withrespect to the width direction. In other words, the one positiveelectrode end is located more exteriorly than the first separator endwith respect to the width direction. This one positive electrode end iscomposed of, for instance, an uncoated positive electrode portion (or apart thereof) of the positive electrode plate which portion is notcoated with the positive electrode mixture layer. In this case, thepositive electrode plate and the positive terminal can be electricallyconnected to each other by welding the one positive electrode end to thepositive terminal.

The second separator end is located more interiorly than an othernegative electrode end with respect to the width direction which end islocated at an other end of the negative electrode plate with respect tothe width direction. In other words, the other negative electrode end islocated more exteriorly than the second separator end with respect tothe width direction. This other negative electrode end is composed of,for instance, an uncoated negative electrode portion (or a part thereof)of the negative electrode plate which portion is not coated with thenegative electrode mixture layer. In this case, the negative electrodeplate and the negative terminal are electrically connected to each otherby welding the other negative electrode end to the negative terminal.

Further, with respect to the width direction, the first separator end islocated more exteriorly than one end of a coated positive electrodeportion of the positive electrode plate which portion is coated with thepositive electrode mixture layer and located more exteriorly than oneend (that corresponds to one end of the negative electrode plate) of acoated negative electrode portion of the negative electrode plate whichportion is coated with the negative electrode mixture layer. Inaddition, the first separator end is thermally shrunken by heatingbeforehand (i.e., the first separator end is thermally shrunken byheating during the process of manufacturing the electrode body).

Further, with respect to the width direction, the second separator endis located more exteriorly than an other end (that corresponds to another end of the positive electrode plate) of the coated positiveelectrode portion and located more exteriorly than an other end of thecoated negative electrode portion. In addition, the second separator endis thermally shrunken by heating beforehand (i.e., the second separatorend is thermally shrunken by heating during the process of manufacturingthe electrode body).

Therefore, use of the above-described electrode body in a non-aqueouselectrolyte secondary battery makes it possible to prevent “theundesirable electric short circuit caused by the contact between thepositive electrode plate and the negative electrode plate at thewidthwise ends due to heat shrinkage of the separator in the widthdirection”.

Specifically, even if the separator is heated by heat generation of thebattery to a temperature that causes the separator to thermally shrinkin the width direction, the first and second separator ends are unlikelyto thermally shrink further in the width direction because they havealready been thermally shrunken by heating beforehand. This enables itto keep the separator present between the positive and negativeelectrode plates with respect to the width direction, therebymaintaining the electrical insulation between the positive and negativeelectrode plates.

According to another aspect of the invention, there is provided anelectrode body for use in non-aqueous electrolyte secondary battery, theelectrode body comprising a positive electrode plate, a negativeelectrode plate and a separator interposed between the positive andnegative electrode plates, the positive electrode plate, negativeelectrode plate and separator overlapping one another with their widthsoriented in the same direction, wherein the positive electrode plate hasa positive current collector and a positive electrode mixture layerapplied to a surface of the positive current collector; the negativeelectrode plate has a negative current collector and a negativeelectrode mixture layer applied to a surface of the negative currentcollector; the separator has a first end located at one end thereof anda second end located at the other end thereof with respect to a widthdirection and has an intermediate portion located between the first andsecond ends; with respect to the width direction, the first separatorend is located more interiorly than one positive electrode end which islocated at one end of the positive electrode plate with respect to thewidth direction; located more exteriorly than one end of a coatedpositive electrode portion of the positive electrode plate which portionis coated with the positive electrode mixture layer; and located moreexteriorly than one end of a coated negative electrode portion of thenegative electrode plate which portion is coated with the negativeelectrode mixture layer, the first separator end being heat-welded to aportion of the positive electrode plate which portion is opposed to theseparator in its thickness direction; and with respect to the widthdirection, the second separator end is located more interiorly than another negative electrode end which is located at an other end of thenegative electrode plate with respect to the width direction; locatedmore exteriorly than an other end of the coated positive electrodeportion; and located more exteriorly than an other end of the coatednegative electrode portion, the second separator end being heat-weldedto a portion of the negative electrode plate which portion is opposed tothe separator in its thickness direction.

In the above-described electrode body for use in non-aqueous electrolytesecondary battery, the first separator end is located more interiorlythan one positive electrode end with respect to the width directionwhich end is located at one end of the positive electrode plate withrespect to the width direction. In other words, the one positiveelectrode end is located more exteriorly than the first separator endwith respect to the width direction. This one positive electrode end iscomposed of, for instance, an uncoated positive electrode portion (or apart thereof) of the positive electrode plate which portion is notcoated with the positive electrode mixture layer. In this case, thepositive electrode plate and the positive terminal can be electricallyconnected to each other by welding the one positive electrode end to thepositive terminal.

The second separator end is located more interiorly than an othernegative electrode end with respect to the width direction which end islocated at an other end of the negative electrode plate with respect tothe width direction. In other words, the other negative electrode end islocated more exteriorly than the second separator end with respect tothe width direction. This other negative electrode end is composed of,for instance, an uncoated negative electrode portion (or a part thereof)of the negative electrode plate which portion is not coated with thenegative electrode mixture layer. In this case, the negative electrodeplate and the negative terminal are electrically connected to each otherby welding the other negative electrode end to the negative terminal.

Further, with respect to the width direction, the first separator end islocated more exteriorly than one end of the coated positive electrodeportion of the positive electrode plate which portion is coated with thepositive electrode mixture layer and located more exteriorly than oneend (that corresponds to one end of the negative electrode plate) of thecoated negative electrode portion of the negative electrode plate whichportion is coated with the negative electrode mixture layer. Inaddition, the first separator end is heat-welded to a portion of thepositive electrode plate which portion is opposed to the separator inits thickness direction (specifically, during the process ofmanufacturing the electrode body, the first separator end is heat-weldedto the portion of the positive electrode plate which portion is opposedto the separator in its thickness direction).

Further, with respect to the width direction, the second separator endis located more exteriorly than an other end (that corresponds to another end of the positive electrode plate) of the coated positiveelectrode portion and located more exteriorly than an other end of thecoated negative electrode portion. In addition, the second separator endis heat-welded to a portion of the negative electrode plate whichportion is opposed to the separator in its thickness direction(specifically, during the process of manufacturing the electrode body,the second separator end is heat-welded to the portion of the negativeelectrode plate which portion is opposed to the separator in itsthickness direction).

Therefore, use of the above-described electrode body in a non-aqueouselectrolyte secondary battery makes it possible to prevent “theundesirable electric short circuit caused by the contact between thepositive electrode plate and the negative electrode plate at thewidthwise ends due to heat shrinkage of the separator in the widthdirection”.

Specifically, even if the separator is heated by heat generation of thebattery to a temperature that causes the separator to thermally shrinkin its width direction, the first and second separator ends are unlikelyto thermally shrink further in the width direction because they havealready been thermally shrunken by heating at the time of heat-welding.In addition, since the first and second separator ends are adhered(heat-welded) to the portions of the positive and negative electrodeplates respectively which portions are opposed to the separator, theinward displacement of the first and second separator ends in the widthdirection can be prevented even if heat shrinkage forces them to moveinwardly in the width direction. This enables it to keep the separatorpresent between the positive and negative electrode plates with respectto the width direction, thereby maintaining the electrical insulationbetween the positive and negative electrode plates.

In the above-described electrode body for use in non-aqueous electrolytesecondary battery, preferably, the portion of the positive electrodeplate to which the first separator end is heat-welded is at least a partof an uncoated positive electrode portion of the positive electrodeplate which portion is not coated with the positive electrode mixturelayer, whereas the portion of the negative electrode plate to which thesecond separator end is heat-welded is at least a part of an uncoatednegative electrode portion of the negative electrode plate which portionis not coated with the negative electrode mixture layer.

In the above-described electrode body for use in non-aqueous electrolytesecondary battery, the portion of the positive electrode plate to whichthe first separator end is heat-welded is at least a part of theuncoated positive electrode portion (where the positive currentcollector is exposed) of the positive electrode plate which portion isnot coated with the positive electrode mixture layer. In other words,the first separator end is heat-welded to the uncoated positiveelectrode portion (or at least a part thereof) of the positive electrodeplate which portion is not coated with the positive electrode mixturelayer. This enables proper adhesion (heat-welding) of the firstseparator end to the positive electrode plate.

In the above-described electrode body for use in non-aqueous electrolytesecondary battery, the portion of the negative electrode plate to whichthe second separator end is heat-welded is at least a part of theuncoated negative electrode portion (where the negative currentcollector is exposed) of the negative electrode plate which portion isnot coated with the negative electrode mixture layer. In other words,the second separator end is heat-welded to the uncoated negativeelectrode portion (or at least a part thereof) of the negative electrodeplate which portion is not coated with the negative electrode mixturelayer. This enables proper adhesion (heat-welding) of the secondseparator end to the negative electrode plate.

According to still another aspect of the invention, there is provided anon-aqueous electrolyte secondary battery comprising any one of theabove-described electrode bodies for use in non-aqueous electrolytesecondary battery.

The above non-aqueous electrolyte secondary battery is provided with anyone of the above-described electrode bodies for use in non-aqueouselectrolyte secondary battery. Therefore, the above-describednon-aqueous electrolyte secondary battery makes it possible to prevent“the undesirable electric short circuit caused by the contact betweenthe positive electrode plate and the negative electrode plate at thewidthwise ends due to heat shrinkage of the separator in the widthdirection”.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a top view of a non-aqueous electrolyte secondary battery infirst to third embodiments;

FIG. 2 is a front view of the non-aqueous electrolyte secondary battery;

FIG. 3 is a longitudinal sectional view of the non-aqueous electrolytesecondary battery, taken along a line C-C in FIG. 1;

FIG. 4 is a longitudinal sectional view of the non-aqueous electrolytesecondary battery, taken along a line D-D in FIG. 1;

FIG. 5 is a perspective view of an electrode body of the non-aqueouselectrolyte secondary battery;

FIG. 6 is a cross sectional view of the electrode body in the firstembodiment, taken along a line E-E in FIG. 3;

FIG. 7 is a top view of a positive electrode plate in the first to thirdembodiments;

FIG. 8 is a sectional view of the positive electrode plate, taken alonga line F-F in FIG. 7;

FIG. 9 is a top view of a negative electrode plate in the first to thirdembodiments;

FIG. 10 is a sectional view of the negative electrode plate, taken alonga line G-G in FIG. 9;

FIG. 11 is a top view of a separator in the first embodiment;

FIG. 12 is a sectional view of the separator taken along a line H-H inFIG. 11;

FIG. 13 is an explanatory view showing a process of manufacturing theelectrode body in the first embodiment;

FIG. 14 is a cross sectional view of an electrode body in the secondembodiment, taken along the line E-E in FIG. 3;

FIG. 15 is a top view of a separator in the second embodiment;

FIG. 16 is an explanatory view showing a thermal treatment step in thesecond embodiment;

FIG. 17 is an explanatory view showing a process of manufacturing theelectrode body in the second embodiment;

FIG. 18 is a cross sectional view of an electrode body in the thirdembodiment, taken along the line E-E in FIG. 3; and

FIG. 19 is an explanatory view showing a process of manufacturing theelectrode body in the third embodiment.

DESCRIPTION OF EMBODIMENTS First Embodiment

Referring now to the accompanying drawings, the invention will bedescribed according to a first embodiment.

As shown in FIGS. 1 to 4, a non-aqueous electrolyte secondary battery100 constructed according to the first embodiment is a rectangularsealed lithium ion secondary battery having a rectangular parallelepipedbattery case 110, a positive terminal 120 and a negative terminal 130.Of these components, the battery case 110 is a hard case composed of ametallic rectangular storage section 111 and a metallic lid 112, thestorage section 111 including a rectangular parallelepiped storagespace. Disposed within the battery case 110 (rectangular storage section111) are an electrode body 150 and others. The rated capacity (nominalcapacity) of the non-aqueous electrolyte secondary battery 100 is 5.5Ah.

The electrode body 150 is a flat rolled-up body having an oval-shapedcross section and composed of a positive electrode plate 155, a negativeelectrode plate 156 and a separator 157 which are wound into a flatshape (see FIGS. 4 to 13). The positive electrode plate 155, thenegative electrode plate 156 and the separator 157 overlap one anotherwith their widths oriented in the same direction (see FIGS. 6 and 13).It should be noted that the longitudinal directions (perpendicular tothe width directions) of the positive electrode plate 155, the negativeelectrode plate 156 and the separator 157 coincide with the windingdirection. The lateral directions of FIGS. 6 and 13 coincide with therespective width directions of the positive electrode plate 155, thenegative electrode plate 156 and the separator 157 and with the widthdirection of the electrode body 150.

The positive electrode plate 155 is strip-like in shape and includes apositive current collector 151 made of aluminum foil and positiveelectrode mixture layers 152 (i.e., mixture layers containing a positiveactive material 153) applied to the surfaces (both surfaces),respectively, of the positive current collector 151 (see FIGS. 7 and 8).The positive electrode plate 155 is composed of a coated positiveelectrode portion 155 d in which the surfaces of the positive currentcollector 151 are coated with the positive electrode mixture layers 152respectively and an uncoated positive electrode portion 155 b in whichthe surfaces of the positive current collector 151 are not coated withthe positive electrode mixture layers 152. The uncoated positiveelectrode portion 155 b is composed of only the positive currentcollector 151 and located at one end of the positive electrode plate 155with respect to the width direction (located at the right end in FIGS.7, 8), extending in the longitudinal direction of the positive electrodeplate 155. The lateral directions of FIGS. 7 and 8 coincide with thewidth direction of the positive electrode plate 155. The verticaldirection of FIG. 7 coincides with the longitudinal direction of thepositive electrode plate 155. The vertical direction of FIG. 8 coincideswith the thickness direction of the positive electrode plate 155.

The negative electrode plate 156 is strip-like in shape and includes anegative current collector 158 made of copper foil and negativeelectrode mixture layers 159 (mixture layers containing a negativeactive material 154) applied to the surfaces, respectively, of thenegative current collector 158 (see FIGS. 9 and 10). The negativeelectrode plate 156 is composed of a coated negative electrode portion156 d in which the surfaces of the negative current collector 158 arecoated with the negative electrode mixture layers 159 respectively andan uncoated negative electrode portion 156 b in which the surfaces ofthe negative current collector 158 are not coated with the negativeelectrode mixture layers 159. The uncoated negative electrode portion156 b is composed of only the negative current collector 158 and locatedat the other end of the negative electrode plate 156 with respect to thewidth direction (located at the left end in FIGS. 9, 10), extending inthe longitudinal direction of the negative electrode plate 156. Thelateral directions of FIGS. 9 and 10 coincide with the width directionof the negative electrode plate 156. The vertical direction of FIG. 9coincides with the longitudinal direction of the negative electrodeplate 156. The vertical direction of FIG. 10 coincides with thethickness direction of the negative electrode plate 156.

The separator 157 is composed of apolypropylene-polyethylene-polypropylene trilaminar composite poroussheet and has a strip shape (see FIGS. 11 and 12). This separator 157 isinterposed between the positive electrode plate 155 and the negativeelectrode plate 156 so as to provide electrical insulation between them(see FIG. 6). It should be noted that the lateral directions of FIGS. 11and 12 coincide with the width direction of the separator 157. Thevertical direction of FIG. 9 coincides with the longitudinal directionof the negative electrode plate 156. The vertical direction of FIG. 10coincides with the thickness direction of the negative electrode plate156.

The separator 157 has a first end 157 b, a second end 157 c and anintermediate portion 157 d. When viewed in the width direction, thefirst end 157 b is located at one end (the right end in FIGS. 11, 12),the second end 157 c is located at the other end (the left end in FIGS.11, 12), and the intermediate portion 157 d is located between the firstend 157 b and the second end 157 c.

As shown in FIG. 6, in the electrode body 150 of the first embodiment,the first end 157 b of the separator 157 is located more interiorly than(located closer to the center of the electrode body 150 than) onepositive electrode end 155 c is, with respect to the width direction(lateral direction in FIG. 6), the end 155 c being located at one end(right end in FIG. 6) of the positive electrode plate 155 with respectto the width direction. In other words, the one positive electrode end155 c is located more exteriorly than (is more distant from the centerof the electrode body 150 than) the first end 157 b of the separator 157is, with respect to the width direction. This one positive electrode end155 c is constituted by the uncoated positive electrode portion 155 b(or a part thereof) of the positive electrode plate 155. Therefore, thepositive electrode plate 155 and the positive terminal 120 can beelectrically connected to each other by welding the one positiveelectrode end 155 c to a positive current collecting portion 122 of thepositive terminal 120 as described later (see FIG. 3).

In addition, the second end 157 c of the separator 157 is located moreinteriorly than (located closer to the center of the electrode body 150than) an other negative electrode end 156 c is, with respect to thewidth direction (lateral direction in FIG. 6), the end 156 c beinglocated at the other end (left end in FIG. 6) of the negative electrodeplate 156 with respect to the width direction. In other words, the othernegative electrode end 156 c is located more exteriorly than (is moredistant from the center of the electrode body 150 than) the second end157 c of the separator 157 is, with respect to the width direction. Theother negative electrode end 156 c is constituted by the uncoatednegative electrode portion 156 b (or a part thereof) of the negativeelectrode plate 156. Therefore, the negative electrode plate 156 and thenegative terminal 130 can be electrically connected to each other bywelding the other negative electrode end 156 c to a negative currentcollecting portion 132 of the negative terminal 130 as described later(see FIG. 3).

As shown in FIG. 6, in the electrode body 150 of the first embodiment,the first end 157 b of the separator 157 is located more exteriorly than(located, in FIG. 6, on the right side of) one end 155 f of the coatedpositive electrode portion 155 d of the positive electrode plate 155 andlocated more exteriorly than (located, in FIG. 6, on the right side of)one end 156 f (which corresponds to one end of the negative electrodeplate 156) of the coated negative electrode portion 156 d of thenegative electrode plate 156, with respect to the width direction(lateral direction in FIG. 6). In addition, the first end 157 b of theseparator 157 is thicker than the intermediate portion 157 d (see FIGS.6, 12). More specifically, the first end 157 b of the separator 157 isfolded double so as to be thicker than the intermediate portion 157 d(twice thicker than the intermediate portion 157 d).

The second end 157 c of the separator 157 is located more exteriorlythan (located, in FIG. 6, on the left side of) an other end 155 g (whichcorresponds to the other end of the positive electrode plate 155) of thecoated positive electrode portion 155 d of the positive electrode plate155 and located more exteriorly than (located, in FIG. 6, on the leftside of) an other end 156 g of the coated negative electrode portion 156d of the negative electrode plate 156 with respect to the widthdirection (lateral direction in FIG. 6). In addition, the second end 157c of the separator 157 is thicker than the intermediate portion 157 d(see FIGS. 6, 12). More specifically, the second end 157 c of theseparator 157 is folded double so as to be thicker than the intermediateportion 157 d (twice thicker than the intermediate portion 157 d).

Since the non-aqueous electrolyte secondary battery 100 of the firstembodiment has the above-described electrode body 150, it is possible toprevent “the undesirable electric short circuit caused by the contactbetween the positive electrode plate 155 and the negative electrodeplate 156 at the widthwise ends (the lateral ends of the coated positiveelectrode portion 155 d and the coated negative electrode portion 156 din FIG. 6) due to heat shrinkage of the separator 157 in the widthdirection (lateral direction in FIG. 6)”.

Concretely, if the temperature of the non-aqueous electrolyte secondarybattery 100 becomes high for some reason, the separator 157 made ofresin thermally shrinks in the width direction. At that time, the firstend 157 b of the separator 157 moves inwardly in the width direction(toward the left in FIG. 6) while the second end 157 c moving inwardlyin the width direction (toward the right in FIG. 6).

However, in the separator 157 of the first embodiment, the first end 157b of the separator 157 strikes against the end face of the one end 155 fof the coated positive electrode portion 155 d or the one end 156 f ofthe coated negative electrode portion 156 d and therefore cannotinwardly move further in the width direction (to the left in FIG. 6),because the first end 157 b and the second end 157 c are thicker thanthe intermediate portion 157 d. This enables it to prevent “theundesirable contact between the one end 155 f of the coated positiveelectrode portion 155 d and the one end 156 f of the coated negativeelectrode portion 156 d which contact is caused by the first end 157 bof the separator 157 getting into the interface between the positiveelectrode plate 155 (coated positive electrode portion 155 d) and thenegative electrode plate 156 (coated negative electrode portion 156 d)”.It should be noted that the first end 157 b formed by folding theseparator 157 double is softened by heat so that it becomes an integralportion (mass).

The second end 157 c of the separator 157 strikes against the end faceof the other end 155 g of the coated positive electrode portion 155 d orthe other end 156 g of the coated negative electrode portion 156 d andtherefore cannot inwardly move further in the width direction (to theright in FIG. 6). This enables it to prevent “the undesirable contactbetween the other end 155 g of the coated positive electrode portion 155d and the other end 156 g of the coated negative electrode portion 156 dwhich contact is caused by the second end 157 c of the separator 157getting into the interface between the positive electrode plate 155(coated positive electrode portion 155 d) and the negative electrodeplate 156 (coated negative electrode portion 156 d)”. It should be notedthat the second end 157 c formed by folding the separator 157 double issoftened by heat so that it becomes an integral portion (mass).

Therefore, in the non-aqueous electrolyte secondary battery 100 of thefirst embodiment, even if the temperature of the separator 157 rises toa temperature (e.g., 150° C.) that causes heat shrinkage of theseparator 157, the separator can be kept present between the positiveelectrode plate 155 and the negative electrode plate 156 with respect tothe width direction (lateral direction in FIG. 6) of the electrode body150, thereby maintaining the electric insulation between the positiveelectrode plate 155 and the negative electrode plate 156.

Next, the process of manufacturing the non-aqueous electrolyte secondarybattery 100 will be explained.

First, the positive electrode plate 155, having the positive electrodemixture layers 152 applied to the surfaces of the strip-shaped positivecurrent collector 151 as shown in FIGS. 7 and 8, is prepared. Then, thenegative electrode plate 156, having the negative electrode mixturelayers 159 applied to the surfaces of the strip-shaped negative currentcollector 158 as shown in FIGS. 9 and 10, is prepared. Then, theseparator 157, the widthwise ends (the first end 157 b and the secondend 157 c) of which are folded double such that they become thicker thanthe intermediate portion 157 d (twice thicker than the intermediateportion 157 d) as shown in FIGS. 11 and 12, is prepared.

Next, the positive electrode plate 155, the negative electrode plate 156and the separator 157 are wound into a flat roll such that they overlapone another as shown in FIG. 13, whereby the electrode body 150 isformed (see FIG. 5). More specifically, the positive electrode plate155, the negative electrode plate 156 and the separator 157 are arrangedas follows when they are rolled up. With respect to the width direction,the first end 157 b of the separator 157 is located more interiorly than(located, in FIG. 13, on the left side of) the one positive electrodeend 155 c of the positive electrode plate 155; located more exteriorlythan (located, in FIG. 13, on the right side of) the one end 155 f ofthe coated positive electrode portion 155 d of the positive electrodeplate 155; and located more exteriorly than (located, in FIG. 13, on theright side of) the one end 156 f of the coated negative electrodeportion 156 d of the negative electrode plate 156. Further, with respectto the width direction (lateral direction in FIG. 13), the second end157 c of the separator 157 is located more interiorly than (located, inFIG. 13, on the right side of) the other negative electrode end 156 c ofthe negative electrode plate 156; located more exteriorly than (located,in FIG. 13, on the left side of) the other end 155 g of the coatedpositive electrode portion 155 d of the positive electrode plate 155;and located more exteriorly than (located, in FIG. 13, on the left sideof) the other end 156 g of the coated negative electrode portion 156 dof the negative electrode plate 156.

Then, the positive current collecting portion 122 of the positiveterminal 120 is welded to the upper end of the one positive electrodeend 155 c of the electrode body 150 (see FIG. 3). The negative currentcollecting portion 132 of the negative terminal 130 is welded to theupper end of the other negative electrode end 156 c of the electrodebody 150. After this electrode body 150 is accommodated within therectangular storage section 111, the opening of the rectangular storagesection 111 is closed with the lid 112. Thereafter, the lid 112 iswelded to the rectangular storage section 111. Subsequently, anon-aqueous electrolytic solution is poured into the rectangular storagesection 111 through a pouring port (not shown) formed in the lid 112 (atthat time, the electrode body 150 is impregnated with the non-aqueouselectrolytic solution). The pouring port is then sealed and themanufacture of the non-aqueous electrolyte secondary battery 100 of thefirst embodiment is accordingly completed.

Second Embodiment

A non-aqueous electrolyte secondary battery 200 constructed according tothe second embodiment does not differ from the non-aqueous electrolytesecondary battery 100 of the first embodiment except the separator ofthe electrode body. Therefore, the points different from the firstembodiment are mainly discussed herein while explanation of the similaror identical points is omitted or simplified.

Similarly to the first embodiment, a separator 257 of the secondembodiment is composed of a polypropylene-polyethylene-polypropylenetrilaminar composite porous sheet and has a strip shape (see FIG. 15).The separator 257 has a first end 257 b (indicated by hatching in FIG.15) located at one end (right end in FIG. 15) with respect to the widthdirection, a second end 257 c (indicated by hatching in FIG. 15) locatedat the other end (left end in FIG. 15), and an intermediate portion 257d located between the first end 257 b and the second end 257 c. Itshould be noted that the lateral direction of FIG. 15 corresponds to thewidth direction of the separator 157 and the vertical direction of FIG.15 corresponds to the longitudinal direction of the separator 157.

As shown in FIG. 14, in an electrode body 250 of the second embodiment,the first end 257 b of the separator 257 is located more interiorly than(located, in FIG. 14, on the left side of) the one positive electrodeend 155 c with respect to the width direction (lateral direction in FIG.14), the end 155 c being located at one end (right end in FIG. 14) ofthe positive electrode plate 155 with respect to the width direction. Inother words, the one positive electrode end 155 c is located moreexteriorly than (located, in FIG. 14, on the right side of) the firstend 257 b of the separator 257 with respect to the width direction. Thisone positive electrode end 155 c is constituted by the uncoated positiveelectrode portion 155 b (or a part thereof) of the positive electrodeplate 155. Therefore, the second embodiment is also configured such thatthe positive electrode plate 155 and the positive terminal 120 can beelectrically connected to each other by welding the one positiveelectrode end 155 c to the positive current collecting portion 122 ofthe positive terminal 120 (see FIG. 3).

The second end 257 c of the separator 257 is located more interiorlythan (located closer to the center of the electrode body 250 than) theother negative electrode end 156 c is, with respect to the widthdirection (lateral direction in FIG. 14), the end 156 c being located atthe other end (left end in FIG. 14) of the negative electrode plate 156with respect to the width direction. In other words, the other negativeelectrode end 156 c is located more exteriorly than (is more distantfrom the center of the electrode body 250 than) the second end 257 c ofthe separator 257 is, with respect to the width direction. The othernegative electrode end 156 c is constituted by the uncoated negativeelectrode portion 156 b (or a part thereof) of the negative electrodeplate 156. Therefore, the second embodiment is also configured such thatthe negative electrode plate 156 and the negative terminal 130 can beelectrically connected to each other by welding the other negativeelectrode end 156 c to the negative current collecting portion 132 ofthe negative terminal 130 (see FIG. 3).

In addition, the electrode body 250 of the second embodiment isconfigured as shown in FIG. 14. In this figure, the first end 257 b ofthe separator 257 is located more exteriorly than (located, in FIG. 14,on the right side of) the one end 155 f of the coated positive electrodeportion 155 d of the positive electrode plate 155 and located moreexteriorly than (located, in FIG. 14, on the right side of) the one end156 f (that corresponds to the one end of the negative electrode plate156) of the coated negative electrode portion 156 d of the negativeelectrode plate 156, with respect to the width direction (lateraldirection in FIG. 14).

In addition, in the second embodiment, the first end 257 b of theseparator 257 is thermally shrunken by heating beforehand. Moreconcretely, the first end 257 b of the separator 257 is thermallyshrunken by heating to 200° C. in the course of manufacturing theelectrode body 250 (i.e., thermal treatment step) as described later.

Further, the second end 257 c of the separator 257 is located moreexteriorly than (located, in FIG. 14, on the left side of) the other end155 g (which corresponds to the other end of the positive electrodeplate 155) of the coated positive electrode portion 155 d of thepositive electrode plate 155 and located more exteriorly than (located,in FIG. 14, on the left side of) the other end 156 g of the coatednegative electrode portion 156 d of the negative electrode plate 156,with respect to the width direction (lateral direction in FIG. 14).

In addition, in the second embodiment, the second end 257 c of theseparator 257 is thermally shrunken by heating beforehand. Moreconcretely, the second end 257 c of the separator 257 is thermallyshrunken by heating to 200° C. in the course of manufacturing theelectrode body 250 (i.e., thermal treatment step) as described later.

Since the non-aqueous electrolyte secondary battery 200 of the secondembodiment has the above-described electrode body 250, it is possible toprevent “the undesirable electric short circuit caused by the contactbetween the positive electrode plate 155 and the negative electrodeplate 156 at the widthwise ends (the lateral ends of the coated positiveelectrode portion 155 d and the coated negative electrode portion 156 din FIG. 14) due to heat shrinkage of the separator 257 in the widthdirection (lateral direction in FIG. 14)”.

Concretely, since the first end 257 b and second end 257 c of theseparator 257 are thermally shrunken by heating beforehand, they do notthermally shrink any more in the width direction even if the temperatureof the non-aqueous electrolyte secondary battery 200 rises to atemperature (e.g., 150° C.) that causes heat shrinkage of the separator257. More specifically, the first end 257 b of the separator 257 can beprevented from shrinking inwardly in the width direction (to the left inFIG. 14). Also, the second end 257 c can be prevented from shrinkinginwardly in the width direction (to the right in FIG. 14).

This enables it to prevent “the undesirable contact between the one end155 f of the coated positive electrode portion 155 d and the one end 156f of the coated negative electrode portion 156 d which contact is causedby the first end 257 b of the separator 257 getting into the interfacebetween the positive electrode plate 155 (coated positive electrodeportion 155 d) and the negative electrode plate 156 (coated negativeelectrode portion 156 d)”. This further enables it to prevent “theundesirable contact between the other end 155 g of the coated positiveelectrode portion 155 d and the other end 156 g of the coated negativeelectrode portion 156 d which contact is caused by the second end 257 cof the separator 257 getting into the interface between the positiveelectrode plate 155 (coated positive electrode portion 155 d) and thenegative electrode plate 156 (coated negative electrode portion 156 d)”.

Therefore, in the non-aqueous electrolyte secondary battery 200 of thesecond embodiment, even if the temperature of the separator 257 rises toa temperature (e.g., 150° C.) that causes heat shrinkage of theseparator 257, the separator can be kept present between the positiveelectrode plate 155 and the negative electrode plate 156 with respect tothe width direction (lateral direction in FIG. 14) of the electrode body250, thereby maintaining the electric insulation between the positiveelectrode plate 155 and the negative electrode plate 156. Note thatsince the intermediate portion 257 d of the separator 257 is interposedbetween and pressed by the positive electrode plate 155 (coated positiveelectrode portion 155 d) and the negative electrode plate 156 (coatednegative electrode portion 156 d), the intermediate portion 257 d isunlikely to shrink in the width direction even if the temperature of theseparator 257 rises to a temperature (e.g., 150° C.) that causes heatshrinkage of the separator 257.

Next, the process of manufacturing the non-aqueous electrolyte secondarybattery 200 will be explained.

First, the positive electrode plate 155, having the positive electrodemixture layers 152 applied to the surfaces of the strip-shaped positivecurrent collector 151 as shown in FIGS. 7 and 8, is prepared. Then, thenegative electrode plate 156, having the negative electrode mixturelayers 159 applied to the surfaces of the strip-shaped negative currentcollector 158 as shown in FIGS. 9 and 10, is prepared.

In the thermal treatment step, the widthwise ends (the first end 257 band the second end 257 c) of the separator 257 are thermally shrunken byheating.

Concretely, as shown in FIG. 16, the first end 257 b of the separator257 is pinched in its thickness direction by heat rollers 11 and 12heated to 200° C. whereas the second end 257 c of the separator 257 ispinched in its thickness direction by heat rollers 13, 14 heated to 200°C., and the separator 257 is moved in its longitudinal direction whilethe heat rollers 11 to 14 being rotated. Thereby, the first end 257 band second end 257 c of the separator 257 can be thermally shrunken. Inthis way, the separator 257 having the thermally shrunken first end 257b and second end 257 c can be manufactured.

Next, the positive electrode plate 155, the negative electrode plate 156and the separator 157 are wound into a flat roll such that they overlapone another as shown in FIG. 17, whereby the electrode body 150 isformed (see FIG. 5). More specifically, the positive electrode plate155, the negative electrode plate 156 and the separator 257 are arrangedas follows when they are rolled up. With respect to the width direction(lateral direction in FIG. 17), the first end 257 b of the separator 257is located more interiorly than (located, in FIG. 17, on the left sideof) the one positive electrode end 155 c of the positive electrode plate155; located more exteriorly than (located, in FIG. 17, on the rightside of) the one end 155 f of the coated positive electrode portion 155d of the positive electrode plate 155; and located more exteriorly than(located, in FIG. 17, on the right side of) the one end 156 f of thecoated negative electrode portion 156 d of the negative electrode plate156. Further, with respect to the width direction, the second end 257 cof the separator 257 is located more interiorly than (located, in FIG.17, on the right side of) the other negative electrode end 156 c of thenegative electrode plate 156; located more exteriorly than (located, inFIG. 17, on the left side of) the other end 155 g of the coated positiveelectrode portion 155 d of the positive electrode plate 155; and locatedmore exteriorly than (located, in FIG. 17, on the left side of) theother end 156 g of the coated negative electrode portion 156 d of thenegative electrode plate 156.

Then, the positive current collecting portion 122 of the positiveterminal 120 is welded to the upper end of the one positive electrodeend 155 c of the electrode body 250 (see FIG. 3). The negative currentcollecting portion 132 of the negative terminal 130 is welded to theupper end of the other negative electrode end 156 c of the electrodebody 250. After this electrode body 250 is accommodated within therectangular storage section 111, the opening of the rectangular storagesection 111 is closed with the lid 112. Thereafter, the lid 112 iswelded to the rectangular storage section 111. Subsequently, anon-aqueous electrolytic solution is poured into the rectangular storagesection 111 through the pouring port (not shown) formed in the lid 112(at that time, the electrode body 250 is impregnated with thenon-aqueous electrolytic solution). The pouring port is then sealed andthe manufacture of the non-aqueous electrolyte secondary battery 200 ofthe second embodiment is accordingly completed.

Third Embodiment

A non-aqueous electrolyte secondary battery 300 constructed according tothe third embodiment does not differ from the non-aqueous electrolytesecondary battery 100 of the first embodiment except the electrode body.Therefore, the points different from the first embodiment are mainlydiscussed herein while explanation of the similar or identical points isomitted or simplified.

As shown in FIG. 18, in an electrode body 350 of the third embodiment, afirst end 357 b of a separator 357 is located more interiorly than(located, in FIG. 18, on the left side of) the one positive electrodeend 155 c with respect to the width direction (lateral direction in FIG.18) which end 155 c is located at one end (right end in FIG. 18) of thepositive electrode plate 155 with respect to the width direction. Inother words, the one positive electrode end 155 c is located moreexteriorly than (located, in FIG. 18, on the right side of) the firstend 357 b of the separator 357 with respect to the width direction. Thisone positive electrode end 155 c is constituted by the uncoated positiveelectrode portion 155 b (or a part thereof) of the positive electrodeplate 155. Therefore, the third embodiment is also configured such thatthe positive electrode plate 155 and the positive terminal 120 can beelectrically connected to each other by welding the one positiveelectrode end 155 c to the positive current collecting portion 122 ofthe positive terminal 120 (see FIG. 3).

A second end 357 c of the separator 357 is located more interiorly than(located closer to the center of the electrode body 350 than) the othernegative electrode end 156 c is, with respect to the width direction(lateral direction in FIG. 18), the end 156 c being located at the otherend (left end in FIG. 18) of the negative electrode plate 156 withrespect to the width direction. In other words, the other negativeelectrode end 156 c is located more exteriorly than (is more distantfrom the center of the electrode body 350 than) the second end 357 c ofthe separator 357 is, with respect to the width direction. The othernegative electrode end 156 c is constituted by the uncoated negativeelectrode portion 156 b (or a part thereof) of the negative electrodeplate 156. Therefore, the third embodiment is also configured such thatthe negative electrode plate 156 and the negative terminal 130 can beelectrically connected to each other by welding the other negativeelectrode end 156 c to the negative current collecting portion 132 ofthe negative terminal 130 (see FIG. 3).

In addition, the electrode body 350 of the third embodiment isconfigured as shown in FIG. 18. In this figure, the first end 357 b ofthe separator 357 is located more exteriorly than (located, in FIG. 18,on the right side of) the one end 155 f of the coated positive electrodeportion 155 d of the positive electrode plate 155 and located moreexteriorly than (located, in FIG. 18, on the right side of) the one end156 f (that corresponds to the one end of the negative electrode plate156) of the coated negative electrode portion 156 d of the negativeelectrode plate 156, with respect to the width direction (lateraldirection in FIG. 18).

In addition, in the third embodiment, the first end 357 b of theseparator 357 is heat-welded to a portion of the positive electrodeplate 155, the portion being opposed to the separator 357 in thethickness direction (this portion is located under the separator 357 inFIG. 18). Specifically, the first end 357 b of the separator 357 isheat-welded to the portion (uncoated positive electrode portion 155 b)of the positive electrode plate 155 which portion is opposed to theseparator 357 in the thickness direction, as described later in theprocess of manufacturing the electrode body 350. In FIG. 18, theseparator 357 in contact with the upper surface of the negativeelectrode plate 156 (coated negative electrode portion 156 d) isheat-welded to the uncoated positive electrode portion 155 b, with thefirst end 357 b being integral with another first end 357 b locatedthereunder.

Additionally, in the third embodiment, the first end 357 b of theseparator 357 is heat-welded to the uncoated positive electrode portion155 b (or a part thereof). Therefore, the first end 357 b of theseparator 357 can be properly adhered (welded) to the positive electrodeplate 155.

Further, the second end 357 c of the separator 357 is located moreexteriorly than (located, in FIG. 18, on the left side of) the other end155 g (which corresponds to the other end of the positive electrodeplate 155) of the coated positive electrode portion 155 d of thepositive electrode plate 155 and located more exteriorly than (located,in FIG. 8, on the left side of) the other end 156 g of the coatednegative electrode portion 156 d of the negative electrode plate 156,with respect to the width direction (lateral direction in FIG. 18).

Additionally, in the third embodiment, the second end 357 c of theseparator 357 is heat-welded to a portion of the negative electrodeplate 156, the portion being opposed to the separator 357 in thethickness direction (in the vertical direction in FIG. 18).Specifically, the second end 357 c of the separator 357 is heat-weldedto the portion (uncoated negative electrode portion 156 b) of thenegative electrode plate 156 which portion is opposed to the separator357 in the thickness direction, as described later in the process ofmanufacturing the electrode body 350.

In the third embodiment, the second end 357 c of the separator 357 isheat-welded to the uncoated negative electrode portion 156 b (or a partthereof). Therefore, the second end 357 c of the separator 357 can beproperly adhered (welded) to the negative electrode plate 156.

Since the non-aqueous electrolyte secondary battery 300 of the thirdembodiment has the above-described electrode body 350, it is possible toprevent “the undesirable electric short circuit caused by the contactbetween the positive electrode plate 155 and the negative electrodeplate 156 at the widthwise ends (the lateral ends of the coated positiveelectrode portion 155 d and the coated negative electrode portion 156 din FIG. 18) due to heat shrinkage of the separator 357 in the widthdirection (lateral direction in FIG. 18)”.

Specifically, even if the temperature of the non-aqueous electrolytesecondary battery 300 rises to a temperature (e.g., 150° C.) that causesheat shrinkage of the separator 357, the first end 357 b and second end357 c of the separator 357 are unlikely to thermally shrink further inthe width direction because they have already been thermally shrunken byheating at the time of heat-welding.

In addition, since the first end 357 b of the separator 357 is adhered(heat-welded) to the portion of the positive electrode plate 155 whichportion is opposed to the separator in the thickness direction, theinward displacement of the first end 357 b of the separator 357 in thewidth direction can be prevented even if it is forced by heat shrinkageto move inwardly in the width direction (to the left in FIG. 18). Thisenables it to prevent “the undesirable contact between the one end 155 fof the coated positive electrode portion 155 d and the one end 156 f ofthe coated negative electrode portion 156 d which contact is caused bythe first end 357 b of the separator 357 getting into the interfacebetween the positive electrode plate 155 (coated positive electrodeportion 155 d) and the negative electrode plate 156 (coated negativeelectrode portion 156 d).

In addition, since the second end 357 c of the separator 357 is adhered(heat-welded) to the portion of the negative electrode plate 156 whichportion is opposed to the separator 357 in the thickness direction, theinward displacement of the second end 357 c of the separator 357 in thewidth direction can be prevented even if it is forced by heat shrinkageto move inwardly in the width direction (to the right in FIG. 18). Thisenables it to prevent “the undesirable contact between the other end 155g of the coated positive electrode portion 155 d and the other end 156 gof the coated negative electrode portion 156 d which contact is causedby the second end 357 c of the separator 357 getting into the interfacebetween the positive electrode plate 155 (coated positive electrodeportion 155 d) and the negative electrode plate 156 (coated negativeelectrode portion 156 d).

Therefore, in the non-aqueous electrolyte secondary battery 300 of thethird embodiment, even if the temperature of the separator 357 rises toa temperature (e.g., 150° C.) that causes heat shrinkage of theseparator 357, the separator can be kept present between the positiveelectrode plate 155 and the negative electrode plate 156 with respect tothe width direction (lateral direction in FIG. 18) of the electrode body350, thereby maintaining the electric insulation between the positiveelectrode plate 155 and the negative electrode plate 156.

Next, the process of manufacturing the non-aqueous electrolyte secondarybattery 300 will be explained.

Firstly, the positive electrode plate 155, having the positive electrodemixture layers 152 applied to the surfaces, respectively, of thestrip-shaped positive current collector 151 as shown in FIGS. 7 and 8,is prepared. Then, the negative electrode plate 156, having the negativeelectrode mixture layers 159 applied to the surfaces, respectively, ofthe strip-shaped negative current collector 158 as shown in FIGS. 9 and10, is prepared. Then, the strip-shaped separator 357, composed of apolypropylene-polyethylene-polypropylene trilaminar composite poroussheet, is prepared.

Next, the positive electrode plate 155, the negative electrode plate 156and the separator 357 are stacked as illustrated in FIG. 19. In thiscase, the positive electrode plate 155, the negative electrode plate 156and the separator 357 are arranged as follows. With respect to the widthdirection (lateral direction in FIG. 19), the first end 357 b of theseparator 357 is located more interiorly than (located, in FIG. 19, onthe left side of) the one positive electrode end 155 c of the positiveelectrode plate 155; located more exteriorly than (located, in FIG. 19,on the right side of) the one end 155 f of the coated positive electrodeportion 155 d of the positive electrode plate 155; and located moreexteriorly than (located, in FIG. 19, on the right side of) the one end156 f of the coated negative electrode portion 156 d of the negativeelectrode plate 156. Further, with respect to the width direction, thesecond end 357 c of the separator 357 is located more interiorly than(located, in FIG. 19, on the right side of) the other negative electrodeend 156 c of the negative electrode plate 156; located more exteriorlythan (located, in FIG. 19, on the left side of) the other end 155 g ofthe coated positive electrode portion 155 d of the positive electrodeplate 155; and located more exteriorly than (located, in FIG. 19, on theleft side of) the other end 156 g of the coated negative electrodeportion 156 d of the negative electrode plate 156.

With the positive electrode plate 155, the negative electrode plate 156and the separator 357 being in such an overlapped condition, the firstend 357 b of the separator 357 and the uncoated positive electrodeportion 155 b of the positive electrode plate 155 are pinched (held inpressure contact) in the thickness direction by the heat rollers 11 and12 heated to 200° C., while the second end 357 c of the separator 357and the uncoated negative electrode portion 156 b of the negativeelectrode plate 156 are pinched (held in pressure contact) in thethickness direction by the heat rollers 13 and 14 heated to 200° C.Then, the positive electrode plate 155, the negative electrode plate 156and the separator 357 are moved in the longitudinal direction (upwardlyin FIG. 19), while the heat rollers 11 to 14 being rotated. Note thatthe heat roller 12 is positioned on the back of the heat roller 11 (onthe farther side when viewed in a direction perpendicular to the planeof the drawing) in FIG. 19, whereas the heat roller 14 is positioned onthe back of the heat roller 13 (on the farther side when viewed in adirection perpendicular to the plane of the drawing) in FIG. 19.

This enables it to heat-weld the first end 357 b of the separator 357 tothe portion (uncoated positive electrode portion 155 b) of the positiveelectrode plate 155 which portion is opposed to the separator 357 in thethickness direction. Further, the second end 357 c of the separator 357can be heat-welded to the portion (uncoated negative electrode portion156 b) of the negative electrode plate 156 which portion is opposed tothe separator 357 in the thickness direction. After heat-welding, they(positive electrode plate 155, negative electrode plate 156 andseparator 357) are wound into a flat roll thereby to form the electrodebody 350 (see FIG. 5).

In the third embodiment, an adhesive agent (e.g., polyolefin-basedadhesive agents) is applied beforehand to the portion (uncoated positiveelectrode portion 155 b) of the positive electrode plate 155 whichportion is opposed to the first end 357 b of the separator 357 in thethickness direction. Also, an adhesive agent (e.g., polyolefin-basedadhesive agents) is applied beforehand to the portion (uncoated negativeelectrode portion 156 b) of the negative electrode plate 156 whichportion is opposed to the second end 357 c of the separator 357 in thethickness direction.

Then, the positive current collecting portion 122 of the positiveterminal 120 is welded to the upper end of the one positive electrodeend 155 c of the electrode body 350 (see FIG. 3). The negative currentcollecting portion 132 of the negative terminal 130 is welded to theupper end of the other negative electrode end 156 c of the electrodebody 350. After this electrode body 350 is accommodated within therectangular storage section 111, the opening of the rectangular storagesection 111 is closed with the lid 112. Thereafter, the lid 112 iswelded to the rectangular storage section 111. Subsequently, anon-aqueous electrolytic solution is poured into the rectangular storagesection 111 through the pouring port (not shown) formed in the lid 112(at that time, the electrode body 350 is impregnated with thenon-aqueous electrolytic solution). The pouring port is then sealed andthe manufacture of the non-aqueous electrolyte secondary battery 300 ofthe third embodiment is accordingly completed.

(Heating Test)

Five samples were prepared for each of the non-aqueous electrolytesecondary batteries 100 to 300 of the first to third embodiments. Also,five non-aqueous electrolyte secondary batteries were prepared as acomparative example which differed from the non-aqueous electrolytesecondary battery 200 of the second embodiment in that the first end andsecond end of the separator had not undergone preliminary heat shrinkage(that is, the thermal treatment step had not been applied to the firstand second ends). A heating test was conducted on these batteries(twenty batteries in total) to check whether internal electric shortcircuit would occur.

First, the capacities of the batteries of the first to third embodimentsand the comparative example (twenty batteries in total) were measured ata temperature of 25° C. prior to the heating test. Specifically, eachbattery was charged with a constant current of 1 C (5.5 A) until thebattery voltage reached 4.2V and then subsequently was charged whilekeeping the battery voltage at 4.2V until the current reached 0.1 C(0.55 A). Thus, the non-aqueous electrolyte secondary battery 100 wascharged up to SOC 100%.

It should be noted that 1 C is the value of current required to completea constant current discharge of the rated capacity (nominal capacity) ofa battery in one hour. The rated capacities (nominal capacities) of thenon-aqueous electrolyte secondary batteries 100 to 300 and thenon-aqueous electrolyte secondary batteries of the comparative exampleare 5.5 Ah, and therefore 1 C=5.5 A.

SOC is the abbreviation of “State of Charge” (=charging rate).

Thereafter, each battery was discharged with a constant current of 1 C(5.5 A) until the battery voltage reached 2.5V. Thus, each battery wasdischarged down to SOC 0%. The quantity of electricity discharged atthat time was measured as the capacity of each battery, and the average(average capacity) of the batteries was calculated for each of the firstto third embodiments and the comparative example. Table 1 shows theresult.

TABLE 1 NUMBER AVERAGE BATTERY MAXIMUM OF CAPACITY VOLTAGE TEMPERATURESHORTED (Ah) (V) (° C.) BATTERIES COM- 5.52 0 210 5 PAR- ATIVE EX- AMPLEEMBOD- 5.48 3.8 160 0 IMENT 1 EMBOD- 5.50 3.8 160 0 IMENT 2 EMBOD- 5.473.8 160 0 IMENT 3

As shown in Table 1, the average capacity of the batteries of the firstembodiment (the average of the capacities of the five sample batteriesprepared for the first embodiment) was 5.48 Ah. The average capacity ofthe batteries of the second embodiment was 5.50 Ah. The average capacityof the batteries of the third embodiment was 5.47 Ah. The averagecapacity of the batteries of the comparative example was 5.52 Ah.

Next, a heating test was conducted on each battery. Specifically, theSOC of each battery was set to 80% (battery voltage=3.8V) and all thebatteries were placed in the test room of heating test equipment. Then,the interior temperature of the test room was raised 5° C. per minute,thereby setting the interior temperature of the test room to 160° C.Thereafter, the internal temperature of the test room was kept at 160°C. and each battery was left to stand in the test room having atemperature of 160° C. for 30 minutes. In the mean time, the temperatureof each battery was measured to obtain the maximum temperature thebattery had reached. It should be noted that 160° C. is a temperaturethat causes heat shrinkage of the separator.

Further, the voltage of each battery was measured during the heatingtest and the battery voltage after the heating test was obtained.Incidentally, in a battery in which internal short circuit has occurred(i.e., the positive electrode plate and the negative electrode platehave come into contact with each other at the widthwise ends of theseparator), the battery voltage generally drops to 0 V. It is thereforeconceivable that, in the batteries whose voltage dropped to 0 V afterthe heating test, the positive electrode plate and the negativeelectrode plate had come into contact with each other at the widthwiseends (first and second ends) of the separator owing to heat shrinkage ofthe separator so that internal short circuit had occurred. Table 1 showsthe result.

As shown in Table 1, the voltages of all the batteries of thecomparative examples dropped to 0 V after the heating test. The maximumtemperature that they reached during the heating test was 210° C. whichwas 50° C. higher than the interior temperature (160° C.) of the testroom. It can be assumed from this result that, in the batteries of thecomparative examples, the positive electrode plate and the negativeelectrode plate came into contact with each other at the widthwise ends(first and second ends) of the separator owing to heat shrinkage of theseparator, causing internal short circuit. The heat generation of thebatteries is thought to be accelerated by this internal short circuit sothat the temperature of the batteries is elevated to 210° C.

The batteries of the first to third embodiments, on the other hand, areall kept at a voltage of 3.8V. The maximum temperature that they reachedduring the heating test was 160° C. which was the same as the interiortemperature (160° C.) of the test room. It is understood from thisresult that the batteries of the first to third embodiments couldmaintain the separator interposed between the positive electrode plateand the negative electrode plate with respect to the width direction ofthe electrode body, keeping the electric insulation between the positiveand negative electrode plates even though they underwent the heatingtest (in which the batteries were heated to a temperature that causesheat shrinkage of the separator). That is, “the undesirable electricshort circuit caused by the contact between the positive electrode plateand the negative electrode plate at the widthwise ends due to heatshrinkage of the separator in the width direction” can be prevented inthe first to third embodiments. The reason for this is as explainedearlier in the description of each embodiment.

The above explanations are provided for the first to third embodiments,but do not limit the invention thereto. The present invention may beembodied in other specific forms without departing from the essentialcharacteristics thereof.

EXPLANATION OF REFERENCE SIGNS

-   -   100, 200, 300 Non-aqueous electrolyte secondary battery    -   110 Battery case    -   150, 250, 350 Electrode body (Electrode body for non-aqueous        electrolyte secondary battery)    -   155 Positive electrode plate    -   155 b Uncoated positive electrode portion    -   155 c One positive electrode end    -   155 d Coated positive electrode portion    -   151 Positive current collector    -   152 Positive electrode mixture layer    -   156 Negative electrode plate    -   156 b Uncoated negative electrode portion    -   156 c Other negative electrode end    -   158 Negative current collector    -   159 Negative electrode mixture layer    -   157, 257, 357 Separator    -   157 b, 257 b, 357 b First end of separator    -   157 c, 257 c, 357 c Second end of separator    -   157 d, 257 d, 357 d Intermediate portion of separator

1. An electrode body for use in non-aqueous electrolyte secondarybattery, the electrode body comprising a positive electrode plate, anegative electrode plate and a separator interposed between the positiveand negative electrode plates, the positive electrode plate, negativeelectrode plate and separator overlapping one another with their widthsoriented in the same direction, wherein the positive electrode plate hasa positive current collector and a positive electrode mixture layerapplied to a surface of the positive current collector; the negativeelectrode plate has a negative current collector and a negativeelectrode mixture layer applied to a surface of the negative currentcollector; the separator has a first end located at one end thereof anda second end located at the other end thereof with respect to a widthdirection and has an intermediate portion located between the first andsecond ends; with respect to the width direction, the first separatorend is located more interiorly than one positive electrode end which islocated at one end of the positive electrode plate with respect to thewidth direction; located more exteriorly than one end of a coatedpositive electrode portion of the positive electrode plate which portionis coated with the positive electrode mixture layer; and located moreexteriorly than one end of a coated negative electrode portion of thenegative electrode plate which portion is coated with the negativeelectrode mixture layer, the first separator end being thicker than theintermediate portion; and with respect to the width direction, thesecond separator end is located more interiorly than an other negativeelectrode end which is located at an other end of the negative electrodeplate with respect to the width direction; located more exteriorly thanan other end of the coated positive electrode portion; and located moreexteriorly than an other end of the coated negative electrode portion,the second separator end being thicker than the intermediate portion. 2.An electrode body for use in non-aqueous electrolyte secondary battery,the electrode body comprising a positive electrode plate, a negativeelectrode plate and a separator interposed between the positive andnegative electrode plates, the positive electrode plate, negativeelectrode plate and separator overlapping one another with their widthsoriented in the same direction, wherein the positive electrode plate hasa positive current collector and a positive electrode mixture layerapplied to a surface of the positive current collector; the negativeelectrode plate has a negative current collector and a negativeelectrode mixture layer applied to a surface of the negative currentcollector; the separator has a first end located at one end thereof anda second end located at the other end thereof with respect to a widthdirection and has an intermediate portion located between the first andsecond ends; with respect to the width direction, the first separatorend is located more interiorly than one positive electrode end which islocated at one end of the positive electrode plate with respect to thewidth direction; located more exteriorly than one end of a coatedpositive electrode portion of the positive electrode plate which portionis coated with the positive electrode mixture layer; and located moreexteriorly than one end of a coated negative electrode portion of thenegative electrode plate which portion is coated with the negativeelectrode mixture layer, the first separator end being thermallyshrunken by heating beforehand; and with respect to the width direction,the second separator end is located more interiorly than an othernegative electrode end which is located at an other end of the negativeelectrode plate with respect to the width direction; located moreexteriorly than an other end of the coated positive electrode portion;and located more exteriorly than an other end of the coated negativeelectrode portion, the second separator end being thermally shrunken byheating beforehand.
 3. An electrode body for use in non-aqueouselectrolyte secondary battery, the electrode body comprising a positiveelectrode plate, a negative electrode plate and a separator interposedbetween the positive and negative electrode plates, the positiveelectrode plate, negative electrode plate and separator overlapping oneanother with their widths oriented in the same direction, wherein thepositive electrode plate has a positive current collector and a positiveelectrode mixture layer applied to a surface of the positive currentcollector; the negative electrode plate has a negative current collectorand a negative electrode mixture layer applied to a surface of thenegative current collector; the separator has a first end located at oneend thereof and a second end located at the other end thereof withrespect to a width direction and has an intermediate portion locatedbetween the first and second ends; with respect to the width direction,the first separator end is located more interiorly than one positiveelectrode end which is located at one end of the positive electrodeplate with respect to the width direction; located more exteriorly thanone end of a coated positive electrode portion of the positive electrodeplate which portion is coated with the positive electrode mixture layer;and located more exteriorly than one end of a coated negative electrodeportion of the negative electrode plate which portion is coated with thenegative electrode mixture layer, the first separator end beingheat-welded to a portion of the positive electrode plate which portionis opposed to the separator in its thickness direction; and with respectto the width direction, the second separator end is located moreinteriorly than an other negative electrode end which is located at another end of the negative electrode plate with respect to the widthdirection; located more exteriorly than an other end of the coatedpositive electrode portion; and located more exteriorly than an otherend of the coated negative electrode portion, the second separator endbeing heat-welded to a portion of the negative electrode plate whichportion is opposed to the separator in its thickness direction.
 4. Theelectrode body for use in non-aqueous electrolyte secondary batteryaccording to claim 3, wherein the portion of the positive electrodeplate to which the first separator end is heat-welded is at least a partof an uncoated positive electrode portion of the positive electrodeplate which portion is not coated with the positive electrode mixturelayer, whereas the portion of the negative electrode plate to which thesecond separator end is heat-welded is at least a part of an uncoatednegative electrode portion of the negative electrode plate which portionis not coated with the negative electrode mixture layer.
 5. Anon-aqueous electrolyte secondary battery comprising the electrode bodyfor use in non-aqueous electrolyte secondary battery set forth inclaim
 1. 6. A non-aqueous electrolyte secondary battery comprising theelectrode body for use in non-aqueous electrolyte secondary battery setforth in claim
 2. 7. A non-aqueous electrolyte secondary batterycomprising the electrode body for use in non-aqueous electrolytesecondary battery set forth in claim
 3. 8. A non-aqueous electrolytesecondary battery comprising the electrode body for use in non-aqueouselectrolyte secondary battery set forth in claim 4.